The America’s Right Health Care Glossary

My endless thanks to new contributor William Harvey for lending his industry expertise to America’s Right. My hope is that, as William continues to contribute, this reference guide will grow. See, when it comes to health care, I’m learning as much from him as you are, and that’s a great, great thing. — Jeff


Comparative Effectiveness

Comparative Effectiveness Researc
h (CER) is the direct comparison of existing health care interventions to determine which work best for which patients and which pose the greatest benefits and harms. The core question of comparative effectiveness research is which treatment works best, for whom, and under what circumstances.


In order to measure how well an intervention works, it must be compared to another intervention. In some cases, for example, this is a comparison of a new drug to a well-established, approved drug; in other cases, it may be a comparison of two well-established treatments (drug and/or device) to each other, to see if one is better than the other in a specific population or situation. The “standard” is called the comparator. If the comparator has an effect in the disease being studied, it is called an “active comparator”.

In some cases, there may be no active comparator available; in such cases, a placebo, or inactive comparator is used. A placebo (often called a “sugar pill”) will ideally have all the physical properties of the active drug and all the chemical properties except for those belonging to the “active ingredient” – this allows the new treatment to be compared without the patient or the investigator knowing whether the patient is getting the new treatment or not.

Cost Effectiveness

One way of comparing two interventions is to see how the cost (defined as total cost of care; or the cost of a part of that care, e.g., outpatient costs, medication costs) over a given period of time is affected by each treatment. One can then create a cost-benefit measure to choose between the interventions. Cost effectiveness can also be used to look at different populations (e.g., young vs old; mild disease vs severe disease) and see whether the choice between interventions can be made more specific to patient characteristics.


In medicine, effectiveness relates to how well a treatment works in practice, as opposed to efficacy, which measures how well it works in clinical trials or laboratory studies.

See the discussion of effectiveness in Efficacy.


In a healthcare context, efficacy indicates the capacity for beneficial change (or therapeutic effect) of a given intervention.

If efficacy is established, an intervention is likely to be at least as good as other available interventions, to which it will have been compared (see comparator). Comparisons of this type are typically made in randomized controlled trials, whereas ‘pragmatic’ trials are used to establish the effectiveness of an intervention.

Efficacy is key to pharmaceutical development, because the Food, Drug and Cosmetics Act, which governs the FDA approval process, requires that a drug be shown to be “safe and effective” in order to be approved. Hence, even though efficacy may give a physician little information on whether a specific drug will work for a specific condition, the demonstration of safety and efficacy are the primary initial goals of most pharmaceutical companies. FDA approval is a key first step in bringing a new medicine to market.

However, while FDA may be concerned with efficacy, other government agencies (notably CMS, which administers Medicare), other payors and health care practitioners are more concerned with effectiveness. These stakeholders deals with “real world” patients, with multiple diseases, taking multiple medicines, and dealing with the practical issues of how medicine is practiced, rather than the highly restricted, controlled populations and circumstances of a randomized control trial. Because of this difference in the underlying conditions of “research” vs “practice”, efficacy studies and effectiveness studies often come to very different conclusions about the optimal way a particular medicine should be used to best effect in medical practice.


An intervention is anything done by a health care professional to a patient with the intent of changing the disease process. This could include:

  • prescribing a medicine ( for the patient to take;
  • a surgical procedure;
  • some form of alternative care (meditation; treatment with alternative medications; nutritional or nutriceutical therapy);
  • psychologic or psychiatric counseling; and
  • meditation; and/or prayer.

Randomized Controlled Trial (RCT)

A randomized controlled trial (RCT) is a type of scientific experiment most commonly used in testing the efficacy or effectiveness of healthcare services (such as medicine or nursing) or health technologies (such as pharmaceuticals, medical devices or surgery). As their name suggests, RCTs involve the random allocation of different interventions (e.g., treatments) to subjects. As long as numbers of subjects are sufficient, this ensures that both known and unknown confounding factors are evenly distributed between treatment groups.


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